Numerous types of instruments have been devised for performing laparoscopic tubal coagulation operations. Such instruments are broadly characterized by having a handle grip, a pair of electrodes supported on a probe element for extension from the grip and which electrodes terminate at their distal ends in a pair of tube engaging portions. An external power source leads into the handle grip and a foot or manually actuatable switch or button on the grip permits the operator to selectively apply current to the electrodes from the external power source. In performing tubal coagulation with a bipolar device, customarily the electrodes are passed through a trocar which has been inserted into the abdominal cavity, and the electrode tips are advanced to an open or spread-apart position so that they can be placed on opposite sides of the tube, after which the tips are advanced to a closed position in which the tube is engaged between the tips and current applied thereto for discharge between the electrodes tips so as to coagulate the tube. The same procedure is followed for each tube and may be repeated a number of times for each tube so as to assure complete coagulation and closure. Representative U.S. patents which disclose instruments of the type described are Rioux U.S. Pat. No. 3,938,527; and Bovie U.S. Pat. No. 1,813,902. Other U.S. patents of general interest pertaining to electrosurgical forcep instruments are Herman U.S. Pat. No. 1,731,069; and Bagley U.S. Pat. No. 3,100,489.
Further, laparoscopic instruments can either be categorized as monopolar or bipolar. In monopolar coagulation, a single electrode is energized and electric current is directed between the electrode and a dispersive pad or plate upon which the patient is placed. In bipolar instruments, the current discharge is between a pair of electrodes or electrode tips surrounding the tube thereby avoiding necessity of a dispersive pad or plate. Either in the use of the monopolar or bipolar laparoscopic instruments, it has been proposed in the past to employ a safety interlock or circuit breaker within the handle grip or housing to assure that there will be no electrical current delivered to the electrodes until they are properly positioned in surrounding relation to the tube to be coagulated. The safety interlock is interposed between the electrodes and cable so as to normally open or interrupt the circuit when the electrode tips are in the spaced-apart or spread position; and the circuit is closed so as to permit activation by the switch only when the electrodes are advanced to the tube grasping or closed position. It has also been proposed in various prior art monopolar and bipolar devices to provide for replaceable electrodes or tips so that the handle grip or housing portion of the instrument can be reused for a series of operations merely by replacing the electrodes and probe elements; or for different specific requirements different types of electrodes may be attached to the handle grip member, such as, to perform cutting and coagulation where needed.
Distinct problems arising with the use of the laparoscopic instruments of the type described, especially those having detachable or replaceable electrodes, are to maintain proper sterilization and cleaning, to avoid any possibility of poor electrical connections between the power source and electrodes during the course of an operation, and to establish and maintain a positive but releasable connection between the electrodes and electrode housing so as not to be subject to misalignment or loosening in use. Another drawback has been the placement of the manually activated switch for applying current to the electrodes so as to avoid accidental closure of the switch as the doctor is manuevering and advancing the instrument into proper position for the operation to be carried out.